The phonetic rules that we are going to discuss in this chapter are more or less of a diachronic nature. This means that we deal with the reflections in the contemporary language of sounds or rules that existed in Bulgarian about a millennium ago. We'll pay special attention to three of them - mutation of -Я-, palatalization, and elision of -Е,-Ъ- .

3.4.2. The palatalization of the velar consonants К, Г, Х occurs in three different variants called first, second and third palatalization.

As the name shows, the first palatalization took place before the other two, as early as Common Slavic. Its essence is that the velar consonants К, Г, Х changed into Ч, Ж, Ш when they occurred before certain front vowels. (It should be mentioned that there were at least twice as many front vowels in Common Slavic and in Old Bulgarian as in modern Bulgarian. In the contemporary language there are only two front vowels - e and и).

The results of the second palatalization can be seen mainly in the forms for the plural of the masculine nouns that end on К, Г, Х in the singular. Here are some examples:
вълк : вълци (a wolf : wolves); комик : комици (a comedian : comedians)
биолог : биолози (a biologist : biologists); съпруг : съпрузи (a spouse : spouses)
монах : монаси (a monk : monks); кожух : кожуси (a sheep-skin coat : sheep-skin coats)
The third palatalization took place even later but it did not have considerable impact on Bulgarian, especially from the point of view of a foreigner learning the contemporary language, so we'll skip it and move forward to the next item.

3.4.3. The elision of the vowels -E- and -Ъ- is another phonetic rule that is diachronic by its nature. If the vowels E, Ъ happen to be in the final syllable of nouns or adjectives that belong to the masculine gender they disappear in the forms for the plural and the vocative of the nouns, in the forms for the feminine, the neuter and the plural of the adjectives as well as in the definite forms for the masculine gender of the adjectives. The reason for this is that the -Ъ- comes from Old-Bulgarian -Ъ-, and -E- comes from Old-Bulgarian -Ь-. According a phonetic rule that was in force in Old Bulgarian these vowels were pronounced when they were in a strong position and were not pronounced, i.e. disappeared, when they were in a weak position. We'll not go into details which position was strong, and which - weak, it is enough to point out that in the form for the masculine of the above-mentioned words they are in a strong position and in the rest of the forms they are in a weak position. Here are some examples:
момък : момци; момко, but момъкът (an young man : young men, young man Voc., the young man)
огън : огньове, but огънят (a fire : fires, the fire)
старец : старци; старче, but старецът (an old man : old men, old man Voc., the old man)
орел : орли; орльо, but орелът (an eagle : eagles, eagle Voc., the eagle)
малък : малка, малко, малки, малкия(т) (little/small m : f, n, pl)
топъл : топла, топло, топли, топлия(т) (warm m : f, n, pl)
летен : лятна, лятно, летни, летния(т) (summer attr. m : f, n, pl)
лунен : лунна, лунно, лунни, лунния(т) (moon attr. m : f, n, pl)
As always, there are exceptions to the rule. Thus, in adjectives like зелен, червен, стъклен, дървен, вълнен, копринен etc. the sound e does not disappear when the forms for the feminine, the neuter and the plural, as well as the forms with the definite article for the masculine are constructed:
зелен, зелена, зелено, зелени, зеления(т) (green m : f, n, pl)
вълнен, вълнена, вълнено, вълнени, вълнения(т) (woolen m : f, n, pl)

thanks for the new lesson! I really was waiting for it, I'm gonna start studying it right now

"From relativity ... one obtains an unequivocal proof for the view of philosophers who, like Parmenides, Kant, and the modern idealists, deny the objectivity of change as an illusion or appearance due to our special mode of perception" Gödel.

"From relativity ... one obtains an unequivocal proof for the view of philosophers who, like Parmenides, Kant, and the modern idealists, deny the objectivity of change as an illusion or appearance due to our special mode of perception" Gödel.

So, will you continue with the lessons? (even if I'm the only guy who does the homework) Please. I beg you to do so.

"From relativity ... one obtains an unequivocal proof for the view of philosophers who, like Parmenides, Kant, and the modern idealists, deny the objectivity of change as an illusion or appearance due to our special mode of perception" Gödel.

Plus, a native speaker would rather use the word "следобед" - afternoon. And if you have 5pm, I'd either say "Пет следобед", or "Седемнайсет часа".
"Часа" is often omitted, but it depends on the situation.